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Comments on news posted 2003-07-16 13:02:09: Power line broadband continues to gather momentum despite growing interference concerns. ..
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NoBPLNOW
@rr.com
| Sure, everybody can discover RFI now! I am an electronics engineer and professor at a local college. I have considerable experience in digital, analog and RF systems, having spent much time in the industry prior to beginning to teach 6 years ago. The conversations here are entertaining and enjoyable to read, but there are some additional points to be made.
It seems we all agree that the main problem with DSL and cable distribution is more political in nature than anything else. It also seems that the FCC is intent on approving BPL, and this is also political above all else, even interference problems. All the small-scale tests run so far have been extremely limited in scale and power for several reasons. The most significant of these reasons is that the testers and power companies have a vested interest in making sure that BPL is given the green light.
As has been evidenced time and again, large scale implementation of anything having to do with power distribution never follows the same specifications as the tightly controlled experiments -- IT CANNOT, because there are far too many variables involved which are not present during controlled testing.
Power companies have an extremely poor record of addressing RFI complaints. They know power generation and power distribution, and that is all they are concerned with. In those situations where radio frequency interference occurs, it almost always takes the FCC becoming involved to motivate power companies to remedy the problem. Why? Because the power company doesn't generate (or doesn't THINK they generate) radio frequency signals. In most instances, the complainants simply give up, believing they don't have the resources to fight it. And the power company goes about it's merry way providing power and being either oblivious or unconcerned that RFI (which in their opinion is obviously not their problem) is degrading something else.
When cable television was first introduced, there were many problems with signals that were leaking both out of (egress) and into (ingress) the cable system. It took strict regulation and enforcement to alleviate these problems. The cable system these days is, for the most part, a fairly tight system with little ingress and egress. However, the cable system uses SHIELDED cable which helps greatly with controlling ingress and egress. Power distribution uses UNSHIELDED conductors and will NEVER use shielded cable. The vast majority of the wire used in power distribution isn't even insulated. Alleviating RF radiation from power lines is something that cannot be addressed without removing the RF from the lines. What's the problem with doing that? BPL is digitally modulated radio frequency energy (RF); remove the RF and BPL doesn't exist. Pass BPL (digitally modulated RF) through unshielded wires and it radiates. The unshielded wires become a transmitting antenna.
For those who were asking why BPL won't pass through a transformer, here it is. Rule of electron physics #1: When alternating current passes through a wire, a constantly changing magnetic field is generated around that wire. Rule of electron physics #2: When a changing magnetic field intersects a wire, an alternating current is generated in that wire. Rule of electron physics #3: Wrapping a wire into a coil concentrates the magnetic field into a smaller space and introduces inductance. Rule of electron physics #4: Wrapping a coil of wire around a ferrous core concentrates the magnetic field even more, confining it to a much smaller space, and increases the inductance. BPL uses HF (high frequency) and VHF (Very high frequency) RF energy. The reason that the HF and VHF energy is not transferred from the primary coil to the secondary coil is that the inductance increases the impedance of the primary and secondary coils as the frequency increases. By the time you get into the low HF range the impedance of the transformer is so high that it will allow practically no current to flow. No current, no magnetic field at those frequencies. No magnetic field at those frequencies, no current generated in the secondary. A power transformer will block these higher frequencies almost as well as it will block DC. DC has no changing voltage and current, so it cannot generate the changing magnetic field necessary to magnetically couple the signal from the primary to the secondary.
The HF and VHF RF spectrum contains a plethora of essential services which we simply cannot live without. Commercial aircraft use HF and VHF for communication with towers and weather services. Ships use HF and VHF for communication and navigational information. Government and industry uses HF and VHF for far too many purposes to even list. For these and an incredible number of other communications uses, BPL has the strong potential of major disruption. Whether or not you think you depend on these services is not the issue; YOU DO, and our lives would be extremely compromised if they were rendered ineffective.
So far as the HAMs go, most people don't realize the contribution that HAMS make to our safety. Anyone who has been paying attention during the last three years knows that telephone and cell phones and the internet are prone to failure during disaster situations. The ONLY reliable means of communicating during these times is still HAM radio. Hurricanes, tornados, earthquakes, fires and airplanes have totally disrupted essential communications hundreds of times in the last five years. HAM radio was there to save lives and help in restoring order. These people do this out of a desire to make a difference, they cannot legally accept any payment or compensation for their contributions, and we cannot get by without them. To render such a valuable national and international resource useless would be a terrible mistake. BPL can and will do just that. The convenience of someone having broadband is miniscule compared to someone else's ability to keep living. Hobby radio? Yes. An essential national resource contributing to safety and security? A resounding YES.
Its a crying shame that so much political pressure is being brought to bear on the FCC commissioners to approve BPL. Since the commissioners themselves are creatures of politics, not engineers, there is a serious risk that politics could win out. This would be a terrible mistake that could in the end compromise both our security and our economy.
In the end, if they listen to their own technical staff, I hope the FCC will ascend above the political fray and make the right decision. | |
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CheeseWare
Premium
join:2003-04-24
Burnaby, BC
| Is RFI damage workable at a LAN level? The PLC technology certainly seems to make sense in one's household for home LANs (aka last 100m) if one is willing to live with certain tradeoffs. Main benefit is that one can share an ISP on a LAN in the household without radiating 802.11x (&managing related equipment) or running new wires in that household.
Can the logic used to squash PLC over the last mile be used to also squash it over the last 100m? And the converse: can the same tradeoffs made over the last 100m be applicable to the last mile? If that is case, FCC (and BPL ISPs) may be better off to watch for deployment of the PLC technology at the LAN level, Consumer acceptance, price of equipment, etc...
BPL may not become established until PLC becomes a well established LAN solution in the household. This has however not happened yet for reasons that elude me.
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| Bazz3
join:2003-08-17
2076
|  BPL Banned in Japan, Norway and Holland
The Radio Authority in Britain has published a report in which they say that the promoters cannot achieve the noise levels that are required by HF radio operations.
Remember we are not just talking about amateur radio stations but aviation, marine, military and scores of other services.
One of the biggest problems for BPL is the way in which radio signals are picked up on the power lines. Tests in Holland showed that these signals were as large as the data signals.
In a test in a home the system worked fine in the daytime when there were not many strong radio signals but failed at night when signals were stronger.
Its a dead end and will be very suseptible to receiving interference. What it amounts to is very poor engineering practice to stuff HF radio signals down unshielded cables.
Cheers Bazz Sydney Australia | |
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TechTeacherandExtra
@rr.com
| FEMA weighing in on BPL FEMA has finally weighed in on BPL. Lest anyone still feel the hams are simply trying to maintain their hobby of using "outdated and ancient technology", I post the following article copied from the ARRL Letter. You might also go to the website listed to download and view video shot during actual testing.
==>FEMA SAYS BPL WILL "SEVERELY IMPAIR" ESSENTIAL HF OPERATIONS
A proverbial monkey wrench in the works for BPL? Expressing "grave
concerns" about likely interference from unlicensed Broadband over Power
Line (BPL) systems, the Federal Emergency Management Agency (FEMA) told
the FCC that BPL could "severely impair FEMA's mission-essential HF radio
operations in areas serviced by BPL technology." FEMA responded December 4
to last April's FCC BPL Notice of Inquiry, ET Docket 03-104. Now part of
the Department of Homeland Security--the agency said its primary worry is
BPL's potential impact on the FEMA National Radio System (FNARS) on HF.
FNARS is FEMA's primary command and control backup medium under the
Federal Response Plan.
"FEMA has concluded that introduction of unwanted interference from the
implementation of BPL technology into the high frequency radio spectrum
will result in significant detriment to the operation of FEMA radio
systems such as FNARS," FEMA asserted. "FNARS radio operators normally
conduct communications with signals that are barely above the ambient
noise levels." FNARS HF stations, FEMA said, typically are in residential
areas of the sort that BPL might serve.
As part of the Department of Homeland Security, FEMA's perspectives on BPL
could carry substantial weight at the FCC, which may issue a Notice of
Proposed Rule Making as early as February. The FCC's BPL Notice of Inquiry
has attracted more than 5100 comments--many of them from the amateur
community.
FEMA said BPL also could render useless such "essential communications
services" as the Radio Amateur Civil Emergency Service (RACES), the
Military Affiliate Radio System (MARS) and the Civil Air Patrol. FEMA and
ARRL last year signed a Memorandum of Understanding that focuses on how
Amateur Radio may coordinate with the agency in disasters and emergencies.
Calling the HF spectrum "an invaluable and irreplaceable public safety
resource," FEMA said there's no current alternative to HF in terms of
meeting national security and emergency preparedness requirements at the
national, state and local levels. The agency advised the FCC to beef up
its Part 15 rules to ensure no increase in interference levels to existing
FCC or NTIA-licensed communication systems. Otherwise, FEMA predicted,
"any noise increase inevitably would diminish the ability to maintain
essential communications" and would "directly impair the safety of life
and property."
Likewise, FEMA pointed out, amateur HF transmitters could possibly
interfere with and interrupt BPL service, leading consumers not familiar
with Part 15 to blame licensed radio services.
Concluded FEMA: "The purported benefits of BPL in terms of expanded
services in certain communications sectors do not appear to outweigh the
benefit to the overall public of HF radio capability as presently used by
government, broadcasting and public safety users."
Additional information about BPL and Amateur Radio is on the ARRL Web
site, www.arrl.org/tis/info/html/plc/. To support the League's efforts in
this area, visit the ARRL's secure BPL Web site,
»https://www.arrl.org/forms/development/d···ons/bpl/. | |
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TechTeacherandExtra
@rr.com
| BP: Field Trials in Austria This is quoted from the latest ARRL Letter
==>AUSTRIAN AUTHORITIES PULL PLUG ON BPL PILOT PROJECT
The Austrian Amateur Transmitter Federation (ÖVSV--Österreichischer
Versuchssenderverband) reports that a
Broadband over Power Line (BPL) field test in the city of Linz has been
cut short as a result of excessive radio interference. ÖVSV, Austria's
International Amateur Radio Union (IARU)
member-society, said in December that the Government Ministry for
Commerce, Innovation and Technology closed down Linz Power Company's BPL
pilot project because it was generating interference on the HF bands.
Shortwave broadcaster Radio Austria's futureZone service
says the case that brought the issue to a head
was a Red Cross report that emergency services radio traffic during a
disaster response drill last May was the victim of massive BPL
interference.
"The Commerce Ministry Order not only means the end of the Linz BPL pilot
project," the Radio Austria report said, "but the end of the deployment of
this technology in Austria, especially given the interference to radio
communication in places of business." According to the broadcaster,
measurements were said to have indicated that radiation from the BPL
system exceeded permissible field strength levels by a factor of 10,000.
ÖVSV says radio amateurs in Austria have opposed deployment of all BPL
experiments as neither legal nor compatible with "vital, worldwide
shortwave radiocommunication." Among other problems with BPL, ÖVSV has
cited its potential to disrupt emergency communications and safety-of-life
services as well as military operations on HF and navigation and
aeronautical communication.
Last fall, ÖVSV representatives and Linz amateurs got together with power
company representatives in an effort to resolve BPL's incompatibility with
HF radio operation. The meetings followed news reports of interference to
emergency service communications and QRM complaints from several area
hams. "Because of the racket, expensive installations, such as a 20-meter
monobander on a high-rise building, become totally worthless," ÖVSV said.
The utility agreed to look into the possibility of a 100-meter protective
zone around each amateur's location, notch filters for amateur
frequencies, network system filters and the use of 5 GHz wireless local
area networks. | |
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